Search

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of novel coronavirus disease 2019 (COVID-19), a major cause of atypical pneumonia worldwide. Elderly individuals and those with underlying illnesses, such as cardiovascular and pulmonary diseases, are at a high risk of experiencing severe symptoms and have high mortality rates. There is therefore a major need to develop additional vaccines, effective treatments, and complementary drugs to control this infection. Lactoferrin (LF), a naturally-occurring glycoprotein, is bioactive against viruses and other pathogens. LF has a unique immunomodulatory function and is indispensable for immunity in infants. It is thought to contribute to biological defense in individuals across all generations, not only infants. LF inhibits viral adhesion to host cell surfaces through ionic binding to glycosaminoglycans and/or specific binding to viral structures. Purified LF is cost-effective and orally available as a dietary supplement. Here, we review studies on the protective role of LF against common viral infections. Based on this review, we propose that LF can be a possible prophylactic or therapeutic agent for COVID-19 disease.

Bovine lactoferrin (bLF) is a naturally occurring glycoprotein with antibacterial and antiviral activities. We evaluated whether bLF can prevent viral infections in the human intestinal epithelial cell line Caco-2. To assess antiviral responses, we measured the levels of interferon (IFN) expression, IFN-stimulated gene expression, and infection with a pseudotyped virus bearing either severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein or vesicular stomatitis virus (VSV)-G protein after treatment of cells with both bLF and polyinosinic-polycytidylic acid, an analog of double-stranded RNA that mimics viral infection. Combination treatment of cells with both bLF and polyinosinic-polycytidylic acid increased mRNA and protein expression of several IFN genes ( IFNB, IFNL1, and IFNL2) and IFN-stimulated genes ( ISG15, MX1, IFITM1, and IFITM3) in Caco-2 cells. However, treatment with bLF alone did not induce an antiviral response. Furthermore, combination treatment suppressed infection of the SARS-CoV-2 pseudotyped virus more efficiently than did bLF treatment alone, even though combination treatment increased the expression of mRNA encoding ACE2. These results indicate that bLF increases the antiviral response associated with the double-stranded RNA-stimulated signaling pathway. Our results also suggest that bLF and double-stranded RNA analogs can be used to treat viral infections, including those caused by SARS-CoV-2.

Vitamin A and its derivatives contribute to many physiological processes, including vision, neural differentiation, and reproduction. Vitamin A deficiency causes early cessation of spermatogenesis, characterized by a marked depletion of germ cells. However, there has been no clear understanding about the role of chronic intake of vitamin A excess (VAE) in spermatogenesis. The objective of this study was to investigate whether chronic intake of VAE diet causes arrest of spermatogenesis. To examine the effects of VAE on spermatogenesis, we used ICR male mice fed with control (AIN-93G purified diet: 4 IU/g) diet or VAE (modified AIN-93G diet with VAE: 1,000 IU/g) diet for 7 weeks (from 3 to 10 weeks of age). At 10 weeks of age, the retinol concentration in the testes of VAE mice was significantly higher than that of control mice. Testicular cross sections from control mice contained a normal array of germ cells, while the seminiferous tubules from VAE mice exhibited varying degrees of testicular degeneration. Daily sperm production in VAE testes was dramatically decreased compared to that in control testes. Sperm viability, motility, and morphology were also impaired in VAE mice. Furthermore, we examined the effects of VAE on the expression of genes involved in retinoid signaling and spermatogenesis to determine the underlying molecular mechanisms. Therefore, we are the first to present results describing the long-term dietary intake of VAE impairs spermatogenesis using a mouse model.

Osteoprotegerin (OPG) prevents binding of receptor activator of nuclear factor-kappa B ligand (RANKL) to RANK. Recent studies have reported that immune cell RANK-RANKL interactions are critical to the infection process. Candida albicans is an opportunistic pathogenic fungus and a common cause of candidiasis. This study utilized an orally inoculated mouse model of C. albicans infection to determine whether superficial or systemic candidiasis was associated with alterations in RANK/RANKL/OPG expression. Invasive systemic C. albicans infection increased serum OPG levels in mice. In addition, tongue Opg, Rankl, and Rank mRNA expression were upregulated in mice with superficial oral cavity C. albicans infection. Moreover, administration of exogenous soluble RANKL upregulated Rank and interleukin-10 (Il-10) mRNA in superficially infected tissue, suggesting suppression of localized inflammation. Taken together, these findings suggested that RANK/RANKL/OPG signaling contributes to the pathogenesis of candidiasis. This is the first in vivo study to identify a relationship between this opportunistic infection and the RANK/RANKL/OPG axis.

Platelet-rich fibrin (PRF) is a platelet concentrate derived from complete autologous blood rich in growth factors in the fibrin matrix. Although PRF has been used during oral surgery to optimize wound healing in soft and hard tissue, the precise role of PRF in bone healing remains unclear. The present study assessed the role of PRF in bone remodeling. PRF was prepared from whole blood by low speed centrifugation without any anti-coagulants. Culture of MC3T3-E1 cells with PRF induced the expression of osteoprotegerin (OPG), but had no effect on the expression of receptor activator of nuclear factor-κB ligand (RANKL), increasing the OPG/RANKL ratio. Expression of other osteoblastic differentiation makers, including BMP-2 and -4 and RUNX2, was not affected. PRF filling of a hole defect in the mental foramen bone of rats increased OPG positivity and decreased tartrate-resistant acid phosphatase positivity compared with unfilled control. In conclusion, PRF increased the OPG/RANKL ratio by inducing OPG expression, suggesting that PRF enhances early stage osteogenesis by optimizing osteoblastic differentiation. The present study provides a scientific basis for clinical findings showing that PRF can enhance bone regeneration such as sinus lift.

Yamasaki A, Ito H, Yusa J, Sakurai Y, Okuyama N, Ozawa R. Expression of heat shock proteins, Hsp70 and Hsp25, in the rat gingiva after irradiation with a CO2laser in coagulation mode. J Periodont Res 2010; 45: 323–330. © 2009 John Wiley & Sons A/S Background and Objective: The therapeutic rationale of low-energy pulsed CO2 laser coagulation mode has not been clarified yet. We conducted this study to characterize the effect of low-energy pulsed CO2 laser coagulation mode irradiation of the rat gingiva in terms of the expression of heat shock proteins. Material and Methods: Laser irradiation was achieved with the parameters of 5 W, 600 μs pulse duration, and fluence of 326 J/cm2. The gingiva dissected at different times after irradiation was processed for immunohistochemical examination of the expression of the heat shock proteins, Hsp70 and Hsp25. Results: One hour after irradiation, the epithelial keratinocytes facing the laser wound exhibited an overexpression of Hsp70 in their nucleus. The connective tissue cells facing the laser wound, which included fibroblasts and capillary endothelial cells, showed de novo expression of Hsp70 at 3 h post-irradiation, the level of which peaked at 1 d and thereafter decreased. An enhanced and/or de novo expression of Hsp25 in the connective tissue cells facing the laser wound became evident at 3 h after irradiation, and after 1 d the Hsp25-expressing cells increased in number and spread over the wound as wound repair progressed. There was a temporospatial difference in the expression pattern between Hsp70 and Hsp25, with only a few cells appearing to co-express both heat shock proteins. Conclusion: The CO2 laser treatment in coagulation mode produced the expression of heat shock proteins, and the findings suggest that while Hsp70 mainly conferred cell protection, Hsp25 was involved in the progress of wound repair as well as cell protection.

Background and Objectives This study was conducted to clarify the morphologic characteristics and subsequent repair process of coagulation necrosis produced by pulsed CO2 laser irradiation with relatively low fluence, and thereby to evaluate the clinical efficacy of this irradiation mode. Study Design/Materials and Methods Wounding of rat gingiva to produce coagulation necrosis was done with a CO2 laser with a fluence of 326 J/cm2. The structural characteristics of the wound and subsequent repair process were examined by means of histology, immunohistochemistry, and electron microscopy. Results At 6 hours after irradiation, the cells in the laser wound appeared histologically intact but had lost the immunoreactivity to antibodies against Hsp47 and exhibited various ultrastructural signs of cell death. This wound area was lined by Hsp70-positive cells. At 1-day post-irradiation, the uptake of BrdU rapidly increased in the adjacent epithelium and connective tissue. The re-epithelization commenced at 1 day and was completed by 7 days. The necrotic tissue gradually became integrated within the newly formed connective tissue and the original contour of the gingiva was retained during the repair process. The repair process of the laser-induced wound progressed more rapidly than that of a scalpel-made wound. Conclusions The present study suggests that the coagulation necrosis produced by the low fluence pulsed CO2 laser does not disturb the repair process but promotes its steady progress and subsequent tissue remodeling. This laser mode will pave the way for more conservative and minimally invasive surgery for treating a wide variety of oral soft tissue disorders. Lasers Surg. Med. 40:695–703, 2008. © 2008 Wiley-Liss, Inc.

Background: Transforming growth factor (TGF)-β1 is involved in the pathogenesis of both drug-induced gingival overgrowth and hereditary gingival fibromatosis. Ribozymes enzymatically cleave target mRNAs and are expected to be utilized as the basis of novel nucleic acid-based therapies. We designed a chimeric DNA-RNA ribozyme targeting TGF-β1 mRNA and examined its effect on growth of gingival fibroblasts in culture. Methods: Chimeric DNA-RNA hammerhead ribozyme with sequence complementary to the loop structure of human TGF-β1 mRNA was used. We evaluated transfer of the chimeric ribozyme by hemagglutinating virus of Japan (HVJ)-envelope into cultured human gingival fibroblasts in vitro and rat gingival tissues in vivo. We then examined effects of the chimeric ribozyme to TGF-β1 on proliferation and DNA synthesis in human gingival fibroblasts. We also examined effects of the chimeric ribozyme to TGF-β1 on expression of TGF-β1, type IV collagens, and fibronectin mRNAs and expression of TGF-β1 protein in human gingival fibroblasts. Results: Chimeric ribozyme was sufficiently distributed into human fibroblasts in vitro and rat gingivae in vivo. Chimeric ribozyme to TGF-β1 significantly inhibited expression of TGF-β1, type IV collagen, and fibronectin mRNAs and TGF-β1 protein in human gingival fibroblasts. Mismatch ribozyme had no effect on expression of these molecules. Chimeric ribozyme to TGF-β1 also significantly inhibited proliferation and DNA synthesis in gingival fibroblasts. Conclusion: Chimeric DNA-RNA ribozyme targeting TGF-β1 may be a useful gene therapy agent for treatment of gingival hyperplasia. J Periodontol 2005;76:1265-1274.